1. Field of the Invention
The present invention relates to the production of outer cases for fan flow of multiple flow turbojet engines and more specifically to the integration of an outer ring of the fan outlet on such a case and the means of attaching the guide vanes of the fan outlet to the outer ring.
2. Discussion of the Background
French patent No. FR 2 321 616 in the name of the applicant shows an example of an embodiment of a fan outlet in which each guide vane has a cruciform head screwed onto the case, the fastening screw keeping in position a seal which is supported on the edges of soundproofing panels located upstream and downstream from the fan outlet to restore the exterior boundary wall of the fan flow.
Such a construction has the drawback of requiring two fastening screws for each fan outlet guide vane and fastening screws of the soundproofing panels, which accordingly increases the assembly time and increases the production cost since the number of parts needed for mounting is significant.
On the other hand, compressor stator blades are known from patent No. FR 2 246 185 whose smooth guide vanes are set at the head in a case ring, compressible packings made of metallic braided wires being compressed between the case ring and an outer case screwed on to perform a vibration damping function.
This kind of device described is not very well suited to the production of a fan outlet stage for a multiple flow turbojet engine because it does not permit, or hardly permits, individual disassembly of the fan outlet guide vanes when there is a particular, significant requirement for the maintenance of this part of the engine which is the most subject to impacts from the intake of foreign objects such as hailstones, birds . . .